The present invention relates generally to a cardan type transmission shaft assembly for transmitting torque from an input to an output, the assembly having a pair of universal joints with a connecting shaft therebetween and first and second coupling flanges associated with each universal joint through which torque may be transmitted from an input to an output, and more particularly to an arrangement of axially projecting teeth arranged in groups on the end faces of each of the flanges for transmitting torque from one coupling flange to the other.
Cardan type transmission shafts which have flange couplings of the foregoing type associated with the universal joints of the transmission shaft are usually used for high torque transmission capacity or when it is desired to reduce the amount or size of coupling bolts used for connecting members of the assembly together, such as for connecting an input shaft to one side of one of the universal joints, or for connecting one side of another of the universal joints to an output shaft.
The use of shims or other intermediate friction elements positioned between cooperating end faces of coupling flanges which are used for coupling input or output shafts to one side of a universal joint, are known, such as from German AS No. 1,223,200. When using these arrangements, high friction forces can be developed between the cooperating flanges by the use of appropriate materials so that large amounts of torque can be transmitted by friction between the coupling flanges. The use of such shims or additional friction discs complicate the assembly and increase the cost of the torque transmission assembly rendering such assemblies expensive and impractical.
In another prior arrangement, shown and described in German PS No. 440,816, torque is transmitted from one shaft member to another by using gear arrangements positioned concentric with the joint. The disadvantage of this arrangement, however, is that it is difficult to manufacture since each tooth of the gear arrangement must be formed by a separate cutting operation. In addition to the foregoing, coupling joints having gear arrangements which include groups of teeth extending at right angles to one another, are known. However, these arrangements have the disadvantage that the teeth are likely to be improperly aligned or may become angularly offset during the assembly of a pair of cooperating coupling flanges. Accordingly, unusual care is required to ensure that holes in each flange for receiving coupling bolts are properly aligned with the holes of its cooperating flange.
It is accordingly the principal object of the present invention to provide a transmission shaft assembly having torque transmitting coupling flanges, which overcomes the disadvantages of the prior art.
A more specific object of the present invention is to provide coupling flanges which may be associated with universal joints in a cardan type transmission shaft assembly, which have means for positive engagement with each other for easier assembly, for the elimination of any possible misalignment between the flanges and for ensuring that the bolt holes in each flange will always be aligned with the bolt holes of a cooperating flange when they are assembled.
Yet a further object of the present invention is to provide a novel structure for coupling flanges used in a cardan type transmission assembly, which are relatively inexpensive to manufacture, and which have groups of gear teeth that can be made by low cost manufacturing procedures, such as milling or surface broaching.
Other objects, features and advantages of the present invention will become more apparent from the description of the invention in connection with the accompanying drawings to be described more fully hereinafter.